[AVR][test] Remove test for naked function containing a return.

Summary:
Remove an old test for an explicit return in a naked function from test/CodeGen/AVR/return.ll

clang no longer allows a C return in a naked function.

This test is causing failure of the patch https://reviews.llvm.org/D80715

Reviewers: llvm-commits, dylanmckay

Reviewed By: dylanmckay

Subscribers: Jim

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81099

Change-Id: Id218027e520247ae480b92e7801a660fbe0cf29b

llvm/test/CodeGen/AVR/return.ll

@@ -123,12 +123,6 @@ define i32 @return64_trunc(i32 %a, i32 %b, i32 %c, i64 %d) {
   ret i32 %result
 }
 
-define i32 @naked(i32 %x) naked {
-; CHECK-LABEL: naked:
-; CHECK-NOT: ret
-  ret i32 %x
-}
-
 define avr_intrcc void @interrupt_handler() {
 ; CHECK-LABEL: interrupt_handler:
 ; CHECK: reti